The IPTV video service consumes a lot of bandwidth, and permits no packet loss in the process of transmitting video data. Network bandwidth, especially user link bandwidth, however, is rather limited. To ensure normal running of an IPTV video service and ensure Quality of Service (QoS), a Resource Management (RM) function and a Connection Admission Control (CAC) function need to be deployed in the network.
IPTV services include multicast/broadcast video (such as BTV, i.e., Broadcast TV) and unicast video (such as VOD, i.e., Video-On-Demand). The working mode of a multicast service differs from that of a unicast service sharply, and therefore, the two services implement the CAC function in different ways:
For a multicast service, the multicast CAC is generally performed on an Access Node (AN) locally. That is, when user dial-up is detected and the user requests to join a channel, the AN judges whether the link bandwidth of the user satisfies the bandwidth requirement of the requested channel, or judges whether the number of channels joined by the user exceeds an upper limit. If the link bandwidth of the user is not enough or the number of channels joined by the user exceeds the upper limit, the CAC on the AN fails, and the AN rejects the user's request for joining the channel.
In a unicast service, the unicast CAC function is generally performed by a stand-alone RM server. The RM server knows the network topology and manages the end-to-end bandwidth from the unicast video server to the client. Therefore, when the user requests a unicast video service, a service server requests resources from the RM server, and the RM server judges whether the end-to-end bandwidth satisfies the bandwidth requirement of the unicast video service and returns a resource request result to the service server. Finally, the service server decides, according to the resource request result, whether to admit the service.
In the process of implementing the IPTV service in the prior art, a first solution in the prior art reserves the bandwidth for the multicast service and the unicast service separately. Consequently, the multicast service and the unicast service cannot share bandwidth resources, resulting in a waste of bandwidth resources. Moreover, this solution is applicable to limited scenarios, namely, applicable only if the user link bandwidth is wide enough.
In a second solution in the prior art, the AN reports join information of a multicast user, and the RM server performs CAC uniformly, and this unifies the implementation mode of the CAC for the multicast service and the unicast service.
However, the implementation process is complicated. Moreover, the switching frequency of the multicast service is greater than the switching frequency of the unicast service. Television users switch the channel frequently, resulting in massive information interactions between the AN and the BM server, or between the AN/Broadband Network Gateway (BNG) and the BM server. Consequently, the channel switching duration is long, delay occurs, and the user experience is affected.